Changed vasoconstriction of thoracic aorta induced by simulated microgravity in rats may be associated with altered Rho kinase

AIM:To investigate the vasoconstrictive responsiveness of thoracic aorta and the expression of Rho-associated protein kinase (ROCK) and to explore the relationship between altered ROCK and changed vasoconstriction of thoracic aorta induced by simulated microgravity in rats. METHODS: Four-week tail-suspended (SUS) rats were adopted as the animal models to simulate the main physiological influence on thoracic aorta due to microgravity. Tissue bath was used to measure arterial vasoreactivity and Western blot was applied to detect expression of ROCK II in thoracic aorta. RESULTS: Compared with those in control group, KCl- and phenylephrine-induced contractions both significantly increased in SUS and ROCK-specific inhibitor Y-27632 significantly reduced the aortic contractions induced by both agonists to a similar lower level. Western blot analysis showed that ROCK II expression was significantly upregulated in thoracic aorta in SUS. CONCLUSION: Altered expression and activity of ROCK may play important roles in the increased vasoconstriction of thoracic aorta induced by simulated microgravity in rats. Differences of the thoracic aortic vasoconstriction between simulated microgravity and normal rats could be eliminated by inhibition of ROCK.